Image correction processing is technology to detect a correction parameter from frame picture data to be processed and to make corrections to the frame picture data in accordance with the correction parameter. Conventional image correction processing includes an image slant correction technique and an image stabilization technique.
An image slant correction technique is a technique to estimate an angle of slant (hereafter, “slant angle”), by which the image is slanted with respect to a reference angle, and to correct the image in accordance with the slant angle. An image stabilization technique is a technique to correct shakes shown by frame picture data pieces of frame pictures by stabilizing backgrounds of the frame picture data pieces in the same position, the frame pictures being taken in succession, and the shakes being triggered when taking the frame pictures.
The conventional slant correction technique has been in wide use in the industrial field of optical scanning devices, such as a scanner and a copier. In recent years, an application of such a slant correction technique to the industrial field of imaging apparatuses has also been considered. The slant correction technique has been materialized as products such as an image processing device, a video camera incorporating the stated image processing device, and a program for performing imaging processing.
The following describes the technological significance of an application of a slant correction technique to video cameras. If a video camera operator takes a video with a video camera while walking, then the video camera shakes and moves in accordance with the movement of the operator. Therefore, it is not always the case that the operator can hold the video camera steady in a horizontal orientation while taking a video and walking at the same time. Furthermore, if the operator takes a video without looking into the viewfinder of the video camera, i.e., without watching the video that is actually being taken, then the operator cannot always hold the video camera steady in a horizontal orientation, even thought he/she desires so.
It is a pain to watch a video that was taken with a video camera held in a non-horizontal orientation. In order to make such a slanted video horizontal, the above-described slant correction technique must be used. In the above-described slant correction technique, how to determine the reference angle is a very important issue. Patent Document 1 cited blow discloses technology for performing slant correction by using the slant of an image of the text, which has been read by a scanner, as a reference angle.
Patent Document 1:
Japanese Laid-Open Patent Application No. 2005-184685